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Abstract:

A prosthetic knee provides security and stability, particularly to low
activity users, household and limited community ambulators, single and/or
slow speed ambulators, and those with little voluntary control, while
also balancing walking (dynamic) performance for low activity users. The
prosthetic knee includes a housing, parallel anterior links, a posterior
link, and a chassis. The geometry of the links and their relationship to
one another allow for low voluntary control, shortening of mid-swing,
which reduces stumbling risk, and geometric stability in stance. The
anterior links are particularly oriented, sized and located to provide
for stability. The anterior links both extend above the posterior link
and substantially below the posterior link. The prosthetic knee includes
a friction adjustment mechanism, a stability adjustment mechanism, and an
adjustable extension assist mechanism.

Claims:

1. A prosthetic knee, comprising: a pair of anterior links; at least one
posterior link, the pair of anterior links having a length greater than a
length of the posterior link; a housing connecting the pair of anterior
links and the posterior link, the anterior links connected to the housing
at first upper pivot points, and the posterior link connected to the
housing at second upper pivot points; a chassis connecting the pair of
anterior links and the posterior link, the anterior links connected to
the chassis at first lower pivot points, and the posterior link connected
to the chassis at second lower pivot points; a stability adjustment
mechanism accessible from a front side of the housing and having a stop
element extending from a rear side of the housing and engageable with the
posterior link.

2. The prosthetic knee according to claim 1, further comprising a
friction adjustment mechanism accessible from the front side of the
housing, and cooperating with the pair of anterior links at the first
upper pivot points.

3. The prosthetic knee according to claim 2, wherein the friction
adjustment mechanism defines a friction adjustment screw adjustable from
the front side of the housing and cooperating with a friction pad
engageable with a friction shaft adapted to adjust friction at the first
upper pivot points.

4. The prosthetic knee according to claim 1, further comprising an
extension assist mechanism extending from the chassis toward and
engageable with a posterior link cam.

5. The prosthetic knee according to claim 4, wherein the extension assist
mechanism includes an extension spring extending from a bottom portion of
the chassis and carrying an extension assist piston engaging the
posterior link cam.

6. The prosthetic knee according to claim 5, wherein the posterior link
cam extends beyond the second lower pivot points toward the front side of
the housing.

7. The prosthetic knee according to claim 1, wherein the stability
adjustment mechanism includes a friction adjustment screw accessible from
the front side of the housing and connected to the stop element, the
posterior link engageable with the stop element between the second upper
and lower pivot points.

8. The prosthetic knee according to claim 1, wherein the stop element
defines a rounded tip defining a consistent and smooth surface contact
for the posterior link to strike, thereby easing use of the prosthetic
knee as it enters maximum extension and reducing any noise and impact.

9. The prosthetic knee according to claim 1, wherein a distance between
the first upper and lower pivot points is about twice as much as a
distance between the second upper and lower pivot points.

10. The prosthetic knee according to claim 1, wherein the anterior links
both extend above the posterior link and substantially below the
posterior link.

11. The prosthetic knee according to claim 1, further comprising a
locking mechanism connected to the housing and arranged to arrest
movement of the posterior link near or at the second upper pivot point.

12. The prosthetic knee according to claim 11, wherein the locking
mechanism is pivotable on the housing and biases toward the posterior
link to engage therewith.

13. The prosthetic knee according to claim 12, wherein the posterior link
has a notched portion engageable with the locking mechanism.

14. The prosthetic knee according to claim 12, wherein at least one
spring biases the locking mechanism toward the posterior link.

15. The prosthetic knee according to claim 11, further comprising a block
element mountable on the locking mechanism and preventing engagement of
the locking mechanism with the posterior link.

16. A prosthetic knee, comprising: a pair of anterior links; at least one
posterior link; a housing connecting the pair of anterior links and the
posterior link, the anterior links connected to the housing at first
upper pivot points, and the posterior link connected to the housing at
second upper pivot points; a chassis connecting the pair of anterior
links and the posterior link, the anterior links connected to the chassis
at first lower pivot points, and the posterior link connected to the
chassis at second lower pivot points; a locking mechanism pivotable on
the housing and biases toward the posterior link to engage with a notched
portion formed by the posterior link.

17. The prosthetic knee according to claim 16, wherein at least one
spring extending from the housing biases the locking mechanism toward the
posterior link.

18. The prosthetic knee according to claim 16, further comprising a block
element mountable on the locking mechanism and preventing engagement of
the locking mechanism with the posterior link.

19. A prosthetic knee, comprising: a pair of anterior links; at least one
posterior link; a housing connecting the pair of anterior links and the
posterior link, the anterior links connected to the housing at first
upper pivot points, and the posterior link connected to the housing at
second upper pivot points; a chassis connecting the pair of anterior
links and the posterior link, the anterior links connected to the chassis
at first lower pivot points, and the posterior link connected to the
chassis at second lower pivot points; a stability adjustment mechanism
accessible from a front side of the housing, the stability adjustment
mechanism having a stop element extending from a rear side of the housing
and engageable with the posterior link between the second upper and lower
pivot points, and a friction adjustment screw accessible from the front
side of the housing and connected to the stop element.

20. The prosthetic knee according to claim 19, wherein the stop element
defines a rounded tip defining a consistent and smooth surface contact
for the posterior link to strike, thereby easing use of the prosthetic
knee as it enters maximum extension and reducing any noise.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority from U.S.
Provisional Application No. 61/491,707, filed May 31, 2011, and U.S.
Provisional Application No. 61/644,117, filed on May 8, 2012. This
application incorporates by reference the entirety of U.S. Provisional
Application Nos. 61/491,707 and 61/644,117.

FIELD OF THE INVENTION

[0002] The invention relates to a prosthetic knee, and more particularly
to a prosthetic knee including a four bar geometry.

BACKGROUND

[0003] Artificial limbs, including leg prostheses, employ a wide range of
technologies to provide solutions suitable to many differing needs. For a
trans-femoral amputee, basic needs in a leg prosthesis include stability,
while standing and during the stance phase of a walking gait, and
mechanical compatibility with the walking (or running) gait and some
manner of knee flexion during stance and swing phases of a gait.

[0004] Certain trade-offs exist between security and stability and walking
or running performance (dynamic behavior). A simple, non-articulable leg
(having no movable knee), for example, may provide maximum stability but
does not provide for an ideal gait. Also, sitting may be awkward if a
person cannot bend his knee.

[0005] For low activity users, such as the elderly or persons with other
illnesses, the focus is generally more on providing security and
stability than on providing walking or running performance.

SUMMARY

[0006] Accordingly, a prosthetic knee is disclosed herein that provides
security and stability, particularly to low activity users, household and
limited community ambulators, single and/or slow speed ambulators, and
those with little voluntary control, while also balancing walking
(dynamic) performance for low activity users. Thus, the disclosed
prosthetic knee controls the trade-off between stability and dynamic
behavior. In particular, the disclosed prosthetic knee provides, among
other benefits, a good balance between stability at heel strike and ease
of swing initiation.

[0007] The prosthetic knee may be used to deliver security and stability
to amputees, particularly low activity amputees. The prosthetic knee is a
multi-axial knee having stability adjustment to optimize the balance
between knee stability and dynamic behavior for each individual user. The
prosthetic knee allows for easy kneeling and sitting, and features
increased toe clearance due to mid-swing shortening. Mid-swing shortening
also allows the prosthesis to swing more easily through each step and
helps prevent hip hiking

[0008] The adjustment features of the prosthetic knee (including the
adjustable friction, adjustable stability, and adjustable extension
assist) can all be accessed externally with no disassembly of the
prosthesis required. Thus, a Certified Prosthetist and Orthotist (CPO or
clinician) can match and adjust the prosthetic knee to the individual
user. Specifically, the CPO can adjust the extension assist mechanism to
match a user's fixed walking speed and can adjust the applied friction in
order to prevent excessive heel rise and terminal impact. The adjustable
stability features thus lower stumbling risk, and provide good stability
at heel strike.

[0009] Further, extension assist is provided in the range of 0 degrees to
70 degrees, and the amount of extension assist is easily adjusted by the
CPO without removing the prosthesis from the user's residual limb.

[0010] Additionally, the dynamic behavior of the prosthetic knee, which
may initially be adjusted to be low, can be increased higher as the
user's confidence in using the prosthetic knee increases.

[0011] The large range of adjustability of the stability of the disclosed
prosthetic knee also provides compensation for anterior/posterior offset
problems in the socket used to secure the prosthetic knee to the user's
residual limb.

[0012] The disclosed prosthetic knee also provides excellent knee flexion
(140 degrees, or 180 degrees without the socket attached) to aid with the
user's ability to sit or kneel.

[0013] According to an embodiment of the disclosure, a prosthetic knee
includes a pair of anterior links, and a posterior link. The pair of
anterior links preferably has a length greater than a length of the
posterior link. The prosthetic knee also includes a housing connecting
the pair of anterior links and the posterior link and a chassis
connecting the pair of anterior links and the posterior link. The
anterior link connects to the housing at first upper pivot points, and
the posterior link connects to the housing at second upper pivot points,
whereas the anterior link connects to the chassis at first lower pivot
points, and the posterior link connects to the chassis at second lower
pivot points.

[0014] The prosthetic knee may include a stability adjustment mechanism
accessible from a front side of the housing. The stability adjustment
mechanism has a stop element extending from a rear side of the housing
and engageable with the posterior link between the second upper and lower
pivot points. The stop element may define a rounded tip defining a
consistent and smooth surface contact for the posterior link to strike,
thereby easing use of the prosthetic knee as it enters maximum extension
and reducing any noise or impact.

[0015] The prosthetic knee also may have a friction adjustment mechanism
accessible from the front side of the housing, and cooperating with the
pair of anterior links at the first upper pivot points. The friction
adjustment mechanism preferably defines a friction adjustment screw
adjustable from the front side of the housing and cooperating with a
friction pad engageable with a friction shaft adapted to adjust friction
at the first upper pivot points.

[0016] Likewise, the prosthetic knee may further comprise an extension
assist mechanism extending from the chassis toward and engageable with a
posterior link cam. The extension assist mechanism may have an extension
spring extending from a bottom portion of the chassis and carry an
extension assist piston engaging the posterior link cam. The posterior
link cam may extend beyond the second lower pivot point toward the front
side of the housing.

[0017] The prosthetic knee may further include a locking mechanism that
connects to the housing and arranged to arrest movement of the posterior
link near or at the second upper pivot point. The locking mechanism is
pivotable on the housing and biases toward the posterior link to engage
therewith. The posterior link preferably has a notched portion engageable
with the locking mechanism, and at least one spring biases the locking
mechanism toward the posterior link. The locking mechanism may also
include a block element mountable on the locking mechanism which prevents
engagement of the locking mechanism with the posterior link.

[0018] The prosthetic knee has a four bar geometry which provides for
improved stability. The geometry and size relationships of the various
links and pivot points are selected for greatest toe clearance, improved
stability, and ease of swing initiation and improved maximum flexion. If
the selection of the length of the links is to make them too long, then
this may be poor for leg torsion, whereas if the links are too short,
they are difficult to fit. In accordance with the improved geometry of
the prosthetic knee, for example, the anterior links are preferably
substantially longer than the posterior link, such that a distance
between the first and second upper pivot points is on an order of 2.0-3.0
and a distance between the first and second lower pivot points is on an
order of 5.2-6.2. Various other geometrical configurations are provided
which achieve the desired traits of a prosthetic knee.

[0019] The numerous other advantages, features and functions of
embodiments of a prosthetic knee are readily apparent and better
understood in view of the following description and accompanying
drawings. The following description is not intended to limit the scope of
the prosthetic knee, but instead merely provides exemplary embodiments
for ease of understanding.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] These and other features, aspects, and advantages of the present
invention will become better understood with regard to the following
description, appended claims, and accompanying drawings where:

[0021]FIG. 1A is a schematic view showing a prosthetic leg and foot
assembly.

[0022]FIG. 1 is a front perspective view of a prosthetic knee according
to an embodiment of this disclosure;

[0023]FIG. 2 is a right side view of the prosthetic knee shown in FIG. 1;

[0024] FIGS. 2A and 2B are left side views of the prosthetic knee shown in
FIG. 1 and illustrating the various ratios of locations among the pivot
points and the lengths of the links relative to one another;

[0026] FIGS. 4A and 4B are cross sectional views of the prosthetic knee
taken along line 4-4 in FIG. 3, and showing the prosthetic knee at 0
degrees of flexion and at roughly 30 degrees of flexion, respectively;

[0027] FIG. 5 is a detailed view of the posterior link of the prosthetic
knee shown in FIG. 1;

[0028]FIG. 6 is a right side view of the prosthetic knee shown in FIG. 1
and showing the relationship between the anterior and posterior links
through 0 to 160 degrees of movement; and

[0029] FIGS. 7 and 8 are exploded views of the prosthetic knee shown in
FIG. 1.

[0031]FIG. 9B is a perspective view of a locking pin for the mechanism of
FIG. 9A.

[0032] FIG. 9C is a detailed view showing the mechanism of FIG. 9A in a
locked configuration.

[0033]FIG. 9D is a detailed view showing the mechanism of FIG. 9A in a
position between locked and unlocked configurations.

[0034]FIG. 9E is a detailed view showing the mechanism of FIG. 9A in an
unlocked configuration.

[0035]FIG. 10A is detailed view showing another locking mechanism in a
locked configuration.

[0036]FIG. 10B is a detailed view showing the mechanism of FIG. 10A in an
unlocked configuration.

[0037]FIG. 11A is detailed view showing another locking mechanism in a
locked configuration.

[0038]FIG. 11B is a detailed view showing the mechanism of FIG. 11A in an
unlocked configuration.

[0039]FIG. 12A is a perspective view showing another locking mechanism in
a locked configuration.

[0040] FIG. 12B is a detailed view showing the mechanism of FIG. 12A in a
locked configuration.

[0041]FIG. 12c is a detailed view showing the mechanism of FIG. 12A in an
unlocked configuration.

[0042]FIG. 13A is a perspective view showing the mechanism of FIG. 12A
including a block element.

[0043]FIG. 13B is a cross-sectional view taken along line XIIIB-XIIIB in
FIG. 13A.

[0044] It should be noted that the drawing figures are not necessarily
drawn to scale, but instead are drawn to provide a better understanding
of the components thereof, and are not intended to be limiting in scope,
but rather to provide exemplary illustrations. It should further be noted
that the figures illustrate exemplary embodiments of a prosthetic knee
and the components thereof, and in no way limit the structures or
configurations of prosthetic knee and components thereof according to the
present disclosure.

DETAILED DESCRIPTION

[0045] A. Environment and Context

[0046]FIG. 1A schematically depicts a prosthetic leg and foot assembly
1000 for a residual limb 1010. The assembly 1000 includes a socket
assembly 1002 that embraces the residual limb 1010, a prosthetic knee
1004 connected to the socket assembly 1002 by an adapter 1012, a pylon
1006 connecting the knee 1004, and a foot 1008 connecting to the pylon
1006.

[0047] In order to understand the operation of the prosthetic knee
described herein, a basic discussion of the gait cycle is required. A
gait cycle defines the movement of the leg between successive heel
contacts of the same foot. The gait cycle has two phases: stance and
swing. The stance phase has three time periods: heel-strike, mid-stance
and toe-off.

[0048] At some point during mid-stance, the knee joint will be at full
extension. An actual knee joint will have some flexion between
heel-strike and mid-stance and between mid-stance and toe-off. This is
called "stance flexion." Not all prosthetic joints provide for stance
flexion, and for those that do, they are either mechanically complex,
expensive, or both. Moreover, these prosthetic joints typically require
frequent maintenance and replacement. Additionally, the amount of stance
flexion required can vary from user to user, while most prosthetic joints
have no adjustability.

[0049] Maximum flexion of the knee joint, while walking, will occur at the
end of the toe-off phase. The amount of maximum flexion is typically
determined in part by the speed at which a person is walking The faster a
person walks the greater the amount of maximum flexion, while the slower
a person walks, the lesser amount of maximum flexion. In a natural knee,
the amount of maximum flexion can be controlled and limited via the
musculature of the leg. In a prosthetic knee joint, some artificial means
of controlling and limiting the amount of maximum flexion are typically
provided. Immediately following the end of the toe-off phase begins the
swing phase.

[0050] While the stance phase has three time periods, the swing phase has
two time periods: acceleration and deceleration. The acceleration phase
begins immediately following the maximum flexion during the toe-off
phase. During the acceleration phase, the lower portion of the leg,
consisting of the shin and foot, begins to swing back towards full
extension. In a natural knee joint, a deceleration phase follows the
acceleration phase, during which the lower portion of the leg continues
to swing towards full extension. Some prosthetic joints do not provide
for any deceleration during the swing phase. Other prosthetic joints
provide deceleration by using costly and bulky hydraulic or pneumatic
cylinders. The amount of deceleration required can vary from user to
user, while most prosthetic joints have no adjustability.

[0051] For further ease of understanding the joint disclosed herein, a
description of a few terms is necessary. As used herein, the term "upper"
has its ordinary meaning and refers to a location that is above, or
higher than another location. Likewise, the term "lower" has its ordinary
meaning and refers to a location that is below, or underneath another
location. The term "posterior" also has its ordinary meaning and refers
to a location that is behind or to the rear of another location. The term
"anterior" has its ordinary meaning and refers to a location that is
ahead or to the front of another location. Lastly, the terms "left" and
right" have their ordinary meaning and as used herein refer to the left
and right sides when viewing the prosthetic knee from the anterior side.

[0052] B. Exemplary Embodiment

[0053] An exemplary embodiment of a prosthetic knee 100 is shown in FIGS.
1 and 2. As shown, the prosthetic knee includes a housing 2, parallel
anterior links 4, 5, a posterior link 3, and a chassis 1. The prosthetic
knee 100 includes a pyramid adapter 36 at the top (or a 4-prong adapter)
and a distal tube clamp attachment 128, having a socket head cap screw
(SHCS) 30 for tightening, at the bottom. The geometry allows for low
voluntary control, shortening of mid-swing which reduces stumbling risk,
and geometric stability in stance.

[0054] The anterior links 4, 5 are particularly oriented, sized and
located to provide for stability. Of particular note, the anterior links
4, 5 both extend above the posterior link 3 and substantially below the
posterior link 3. However, the anterior links 4, 5 are not too long for
this leads to poor torsion whereas the anterior links 4, 5 are not too
short for this makes it difficult to fit the prosthetic knee 100.
Preferably, the anterior links 4, 5 are relatively longer than in most if
not all prosthetic knees which allow for increased or longer stability in
a stance phase and which is particularly beneficial to low activity
users.

[0055] In addition to the selection of the length of the links as
parameters for designing the knee, both the flexion factor (i.e., large
angle of locking and easy swing initiation) and a large flexion angle,
which allow for adapter clearance at 130 and 140 degrees, are taken into
consideration. Additional parameters include locating the links for the
greatest toe clearance, good stability, ease of swing initiation, and
good maximum flexion for both the clamp attachment and pyramid adapter.

[0056] In regard to the spatial relationship among the components of the
prosthetic knee, FIGS. 2A and 2B exemplify that the upper anterior pivot
point A at 0 degrees extension is in the same frontal/coronal plane as
the tube clamp attachment 128. This arrangement provides significant
stability to the prosthetic knee and hence the wearer of the knee.

[0057] FIGS. 2A and 2B also show the ranges of various ratios of locations
among the pivot points A, B, C, D and the lengths of the links relative
to one another, taking 1.0 as the base number (representing the vertical
distance between the upper anterior pivot point A and the upper posterior
pivot point C). The vertical distance between the upper anterior pivot
point A and the lower anterior pivot point B is in the range of 9.5-10.5,
and the vertical distance between the upper anterior pivot point A and
the lower posterior pivot point D is in the range of 5-6. Particularly,
the relative locations of the links and their positions relative to
attachments in the form of the pyramid adapter and the clamp attachment
determine their geometry and spatial relationships.

[0058] Turning back to FIG. 1, and as shown in FIGS. 7-8, the housing 2
includes a housing main body 40, with left and right flanges 42, 44 that
protrude from the main body 40 towards the posterior. The left and right
flanges 42, 44 are generally parallel to each other and each include a
pivot pin hole 48. A pivot pin 22 is retained at each end by bearings 25
respectively positioned in the pivot pin holes 48.

[0059] The posterior link 3 has an upper end 54 that includes a pivot pin
hole 56 passing therethrough. The upper end 54 of the posterior link 3 is
positioned between the left and right flanges 42, 44, with the pivot pin
22 passing through the pivot pin holes 48 and pivot pin hole 56. Washers
26 are provided on the pivot pin 22 between the posterior link 3 and each
of the left and right flanges 42, 44.

[0060] The housing main body 40 also includes a friction shaft pivot hole
46 passing therethrough, generally parallel to the pivot pin holes 48 and
pivot pin hole 56. A friction shaft 21 passes through the friction shaft
pivot hole 46, and the ends thereof extend beyond the housing main body
40. Seals 29 and needle bearings 24 are positioned on each end of the
friction shaft 21 within the friction shaft pivot hole 46. Washers 26 are
positioned on each end of the friction shaft 21 adjacent to the housing
main body 40 and the anterior links 4, 5. The anterior links 4, 5 each
define an upper end 64, 74 having a pivot pin hole 66, 76 passing
therethrough, and the opposed ends of the friction shaft 21 are received
in the upper pivot pin holes 66, 76.

[0061] As best seen in FIGS. 7-8, the friction shaft 21 includes an
enlarged diameter portion within the housing main body 40 positioned
between the opposed ends of the friction shaft 21. The enlarged diameter
portion of the friction shaft 21 is provided to be used in the manner
discussed below to provide constant friction and prevent excessive heel
rise and terminal impact.

[0062] A friction screw hole 62 is provided at the anterior portion of the
housing main body 40, generally perpendicular to, and communicating with
the friction shaft pivot hole 46 to expose the enlarged diameter portion
of the friction shaft 21.

[0063] Again, as best seen in FIG. 8, a depending protrusion 50 extends
downwardly from a lower side of the housing main body 40, and has a hole
52 therein for holding and retaining a bumper holder 11, which is
discussed in more detail below. The hole 52 is generally parallel to the
friction screw hole 62. Both the friction screw hole 62 and the hole 52
are generally centrally aligned on the housing main body 40.

[0064] A knee cap cover 31 is positioned along the bottom side of the
housing main body 40 and protects the housing main body 40, for example,
while the user is kneeling. The knee cap cover 31 has an upper surface
that is complementary shaped to the lower surface of the housing main
body 40, including two parallel posterior flange portions, and two
upright anterior portions. The upright anterior portions flank the
friction screw hole 62 when the knee cap cover 31 is assembled with the
housing main body 40. The knee cap cover 31 also includes an anterior
hole 72 aligned with the hole 52 in the housing main body 40 to provide
access to the hole 52 when the knee cap cover 31 is assembled with the
housing main body 40. The knee cap cover 31 is assembled with the housing
main body 40 and the assembly is retained together with screws 35. It
will be recognized that alternative attachment mechanisms, such as bolts,
rivets, adhesives, etc., or a combination thereof, may be used to secure
the knee cap cover 31 to the housing main body 40.

[0065] As seen in FIGS. 1-4, the housing 2 and the chassis 1 are movably
connected to each other by way of the anterior links 4, 5 and the
posterior link 3.

[0066] The relative relationships between the anterior links 4, 5 and
posterior link 3 through 0 to 160 degrees of movement are shown in FIG.
6.

[0067] The structure of the links allows the housing 2 and the chassis 1
to be movably connected, and to move relative to one another as shown in
FIG. 6 can best be seen in FIG. 7. Specifically, each of the anterior
links 4, 5 have a lower end 78, 68 in which a pivot pin hole 80, 70 is
provided. Similarly, the posterior link 3 also has a lower end 58, in
which a pivot pin hole 60 is provided.

[0068] The chassis 1 has a corresponding structure, as discussed below, to
which the lower ends 78, 68, 58 of the respective anterior and posterior
links 4, 5, 3 are pivotally connected. The chassis 1 has a main body 82
with left and right upwardly extending and generally parallel flanges 84,
88. A pivot pin hole 86, 90 is provided in each of the flanges 84, 88 for
receiving bearings 25 and opposed ends of a pivot pin 22, which passes
through the pivot pin hole 30 in the posterior link 3.

[0069] Thus, as can best be seen in the back view of the prosthetic knee
100 shown in FIG. 3, the lower end 58 of the posterior link 3 is
pivotally situated between the upwardly extending flanges 84, 88.
Similarly to the upper end 54 of posterior link 3, as shown in FIG. 7,
washers 26 are provided on the pivot pin 22 between the posterior link 3
and each of the upwardly extending flanges 84, 88.

[0070] Turning back to FIGS. 1 and 7, the main body 82 of the chassis 1
also includes two generally parallel anterior flanges 92, 96, each having
a pivot pin hole 94, 98 formed therein. A pivot pin 23 extends through
the pivot pin holes 94, 98, and into bearings 25 respectively received in
each of the anterior link lower end pivot holes 70, 80. Bolts 28 and
washers 27 are used to secure the lower ends 68, 78 of the anterior links
5, 4 to the pivot pin 23. A chassis cover 32 is provided to aid when the
user is kneeling, and to prevent debris from accumulating on the pivot
pin 23 where it is exposed between the flanges 92, 96.

[0071] Portions of the chassis 1 and the housing 2 are more easily seen in
the back view shown in FIG. 3, including the tube clamp 128, a chassis
access opening 126, and the left and right flanges 42, 44 of the housing
2. The chassis access opening 126 provides access to the extension assist
mechanism, as discussed in more detail below

[0072] FIGS. 4A and 4B illustrate a cross-sectional view of the prosthetic
knee 100 taken along line 4-4 in FIG. 3, where FIG. 4A shows the
prosthetic knee 100 at 0 degrees of flexion and FIG. 4B shows the
prosthetic knee 100 at roughly 30 degrees of flexion. FIGS. 4A and 4B
more clearly show the friction adjustment screw mechanism, the stability
adjustment mechanism, and the extension assist mechanism.

[0073] In reference to FIGS. 3 and 4A-4B, the friction adjustment screw
mechanism includes a friction adjustment screw 6, a friction pad 7, and
the friction shaft 21. The friction adjustment screw mechanism provides
constant friction and prevents excessive heel rise and terminal impact.
For the friction adjustment mechanism, the friction shaft 21 extends into
the friction shaft pivot hole 46 formed on the housing 2. The friction
pad 7 is arranged within the friction screw hole 62 to engage the shaft
21 so as to adjust the friction of the shaft 21 when the friction
adjustment screw 6 is turned. Turning the friction adjustment screw 6 in
a first direction (tightening) increases the amount of friction on the
friction shaft 21, and turning the friction adjustment screw 6 in a
second direction (loosening) decreases the amount of friction on the
friction shaft 21.

[0074] As seen in FIGS. 4A-4B and 8, friction adjustment screw 6 and
friction pad 7 are connected to one another by Belleville washers 8 and a
retainer snap ring 9. The Belleville washers 8, such as disc springs or
spring washers, compensate for wear in the friction adjustment mechanism,
particularly for swing control as in the instant knee 100. Alternative
mechanisms for wear compensation include compression springs or other
suitable biasing mechanisms. The retainer snap ring 9 allows for
controlling the adjustment range, at least one end thereof, for the
constant friction adjustment.

[0075] As also seen in FIGS. 4A-4B and 8 the stability adjustment
mechanism includes a stability adjustment screw 110 connected to a bumper
holder 11 for retaining an extension stop bumper 10. The stability
adjustment mechanism is retained within the hole 52 in the depending
protrusion 50 of the housing main body 40. An extension stop adjustment
ring (retainer ring) 13 and a seal (O-ring) 12 are coaxially provided
with the stability adjustment screw 110 and the bumper holder 11. The
stability adjustment mechanism is a stability setting that balances
between stability and dynamic behavior of the prosthetic knee. It allows
the clinician to match the prosthetic knee to the needs and behavior of
the wearer by tightening or loosening the stability adjustment screw 110,
which alters the position of the extension stop bumper 10 as discussed in
more detail below.

[0076] The retainer snap rings 9, 13 allow for the selection of how the
user can adjust the knee and prevent inadvertent disassembly of the
adjustment mechanism. Specifically, the retainer snap rings 9, 13 can be
set by the clinician to limit the maximum amount of adjustment that can
be made to the prosthetic knee 100 by the user.

[0077] Turning to FIGS. 4A-4B and 7, extension assist mechanism is shown.
The extension assist mechanism includes the extension assist piston 14,
which is retained in an inner housing 15, which remains fixed, along with
an extension assist spring 18. Seals (O-rings) 19 are provided between
the external surface of the extension assist piston 14 and the internal
surface of the inner housing 15

[0078] The upper end of the inner housing 15 is held in a first hole 124
provided in the chassis main body 82 between the upwardly extending
flanges 84, 88, so that the extension assist piston 14 can be biased into
engagement with the lower end 58 of the posterior link 3, as discussed in
detail below.

[0079] An adjustable external housing 16 is provided coaxially with the
inner housing 15 and receives the inner housing 15 (and the extension
assist piston 14) with seal (O-ring) 20 therebetween, as well as a spring
guide 17 and the extension assist spring 18 therein. The spring guide 17
engages a bottom end of the extension assist spring 18, and the upper end
of the extension assist spring 18 engages a bottom end of the extension
assist piston 14. The adjustable external housing 16 is positioned within
the chassis main body 82, extending into the tube portion of the tube
clamp 128.

[0080] By accessing the adjustable external housing 16 through the access
opening 126 (FIG. 3), a clinician can rotate the adjustable external
housing 16 in the vertical direction (upwards or downwards) in order to
alter the compression of the extension assist spring 18, and thus alter
the biasing force applied to the extension assist piston 14 by the
extension assist spring 18, and the biasing force applied to the
posterior link 3 by the extension assist piston 14. In this manner, the
extension assist mechanism allows for adjustment to the individual user's
speed, by adjusting the outer housing.

[0081] A more detailed view of the interaction between the extension
assist piston 14 and the posterior link 3 can be seen in FIG. 5, where
alternate reference numerals are provided to identify specific features.

[0082] As shown in FIG. 5, the posterior link 114 includes an upper cam
surface 118 and a lower cam surface 122 defined on a posterior link cam
121. The stability adjustment screw 110 is connected with the extension
stop bumper 112 which has a rounded tip 116. The upper cam surface 118 is
convex relative to the tip 116 which allows for a consistent and smooth
surface contact for the extension stop bumper 112 to strike, thereby
easing use of the prosthetic knee as it enters maximum extension and
reducing any noise. The lower cam surface 122 is concave relative to the
piston 120 thereby providing consistent and smooth surface contact
between the piston 120 and the posterior link 114.

[0084] As shown in FIG. 7, an anterior link sticker 34 may be provided on
the side anterior links 4, 5 for decorative and/or protective purposes.

[0085] A shin ferrule may be used to provide cosmetic finishing and also
protect the knee from wear and tear.

C. Locking Mechanism Embodiments

[0086] According to the embodiment of FIGS. 9A-9E, a locking mechanism 200
is provided in which a pin lever 210 spring loaded by a coiled spring is
adapted to selectively rotate a pin 202 which locks the posterior link
103 in place or permits it freely rotate. A set screw 216 is used to
position the locking mechanism in position.

[0087] In reference to FIG. 9A, the pin 202 extends through and is
rotatable relative to a portion of the housing 104 and is in engagement
with the posterior link 103. A first end of the pin 204 is secured by a
clip 208 so as to prevent it from slipping from the housing. A second end
of the pin 206 is secured to the pin lever 210. The pin lever 210 is
pivotable in a recess 212 formed by the housing. A set screw 216 movably
extends into an opening 214 of the housing 104, and is generally arranged
perpendicularly to the pin 202 so as to engage therewith.

[0088] An embodiment of the pin 202 is shown in FIG. 9B, wherein the first
end 204 of the pin has a groove 220 that is adapted to receive the clip.
The pin 202 defines an elongate recess 218 having a generally flat
surface 230 for engaging a notch on the posterior link 103. The pin 202
also defines a generally circumferential groove 224 adjacent the second
end of the pin 202 for receiving the set screw 216. The second pin end
also includes an aperture 226 for receiving the pin lever 210.

[0089] FIGS. 9C-9E show various stages of adjustment of the pin lever. In
observing FIG. 9C, the locking mechanism is in a locked configuration
whereby the pin engages the posterior link, and the set screw is
tightened against the pin. The posterior link 103 has a notch 232 with
upper and lower surfaces 234, 236 that correspond to the recess 218 of
the pin 202 such that the lower surface 236 is generally parallel to the
surface 230. The notch 232 effectively engages the pin 202, and prevents
rotation of the posterior link 103.

[0090]FIG. 9D depicts the locking mechanism as it is prepared for an
unlocked configuration. Specifically, the set screw 216 is loosened so as
to allow for rotation of the pin. The pin 202 is turned by the
practitioner by the lever 210, which in turn permits rotation of the
posterior link 103, and the pin 202 clears the way for the posterior link
103 to rotate.

[0091] According to FIG. 9E, once rotation of the posterior link 103 is
permitted, the set screw 216 is tightened to maintain position of the pin
in an unlocked configuration so as to permit rotation of the posterior
link 103.

[0092] FIGS. 10A and 10B illustrate another locking mechanism embodiment.
In this embodiment, a spring loaded latch 250 pivotable about point 252
is accessible from the top exterior portion of the housing 104 (similar
to the following embodiment of FIGS. 12A-12C). The latch 250 is biased
between locked and unlocked positions such that when in the locked
configuration of FIG. 10A, the latch 250 engages the notch 232 on the
posterior link, and in the unlocked configuration of FIG. 10B, the latch
250 is flipped up from the notch 232 to permit rotation of the posterior
link 103.

[0093] FIGS. 11A and 11B depict another locking mechanism embodiment.
According to this embodiment, a locking pin 260 is spring loaded by
spring 262 which prevents the posterior link 103 from moving and biases a
pin head 266 of the pin 260 to engage the notch 232, as show in FIG. 11A
in the locked configuration. FIG. 11B depicts the locking mechanism in an
unlocked configuration wherein the locking pin 260 is pulled by handle
264 away from the notch in order to unlock the posterior link and allow
knee flexion.

[0094] FIGS. 12A-12C show another embodiment of a locking mechanism. In
this embodiment, a latch 302 is secured to an axle 310 rotatable within
an opening 312 in the housing 104. The latch 302 has a rearward end 306
that is received by a recess 314 that is formed by the housing 104, and a
forward end 304 that is engageable with a notch 324 formed by the
posterior link 103. A pair of springs 318, such as elongate coil springs,
are connected to the housing 104 and secured therein 320 are secured to a
pin 316 engaging the forward end 304 of the latch 302. Attachment
elements 322 are mounted on the pin 316 in order to provide a connection
for a lanyard or other suitable connection element used for pulling the
latch 302.

[0095] FIG. 12B shows the locking mechanism 300 in a locked configuration.
In this configuration, the latch forward end 304 has a nose portion 326
engages the notch 324. The latch 302 is biased to engage the notch 324 by
the springs 318. The line of action of the latch contact with the
posterior link is such that the locking mechanism remains locked under
external loading on the knee. FIG. 12c depicts the locking mechanism 300
in an unlocked configuration, wherein a lanyard 332 attaches to the
elements 322, and is used to pull the nose portion 326 from the notch
324, to disengage the latch 302 from the notch, and thereby allow
rotation of the posterior link 103. The latch 302 is configured to have
sufficient clearance so as to allow for complete flexion of the knee.

[0096] FIGS. 13A and 13B show a variation of the embodiment of FIGS. 12A
and 12B that includes a block element 352 for maintaining the knee in an
unlocked configuration. According to this embodiment, the block element
352 attaches to the forward end 304 of the latch 302 by attaching to the
pin 316 by a notched recess 358 that snaps onto the pin 316, and
corresponds to the latch forward end 304. The block element 352 has a
head portion 352 that prevents the latch forward end 304 from engaging
the notch 324. Once secured onto the pin 316, the block element 352
thwarts the forward end 304 from engaging the notch 324.

[0097] The lock prevent element has the advantage of allowing a
practitioner to make the knee so that the wearer can walk on an unlocked
knee, and thereby remove the possibility of the lock from engaging the
posterior link.

D. Conclusion

[0098] It will be recognized that the prosthetic knee and components
thereof can be made from any suitable materials.

[0099] For example, the components can be constructed from an appropriate
material such as those capable of providing lightweight structural
support. Examples of such materials include, but are not limited to,
plastics, steel alloys, aluminum alloys, other metals, ceramics, or other
rigid materials. In an exemplary embodiment, the knee cap cover 31, as
well as the chassis cover 32, may be made from suitable molded plastics.
Additionally, in the exemplary embodiment, the chassis 1, housing 2,
anterior links 4, 5, and posterior link 3 may be made from machined
Aluminum (2024), and may anodized, for example, black or grey. Further,
in the exemplary embodiment, the extension stop bumper can be made of
rubber and the extension spring can be made from spring steel.

[0100] Of course, it is to be understood that not necessarily all objects
or advantages may be achieved in accordance with any particular
embodiment of the invention. Thus, for example, those skilled in the art
will recognize that the invention may be embodied or carried out in a
manner that achieves or optimizes one advantage or group of advantages as
taught herein without necessarily achieving other objects or advantages
as may be taught or suggested herein.

[0101] The skilled artisan will recognize the interchangeability of
various disclosed features from the disclosed embodiments and variations.
In addition to variations described herein, other known equivalents for
each feature can be mixed and matched by one of ordinary skill in the art
to construct a prosthetic knee in accordance with principles of the
present invention.

[0102] Although this invention has been disclosed in the context of
exemplary embodiments and examples, it will be understood by those
skilled in the art that the present invention extends beyond the
specifically disclosed embodiments to other alternative embodiments
and/or uses of the invention and obvious modifications and equivalents
thereof. Thus, it is intended that the scope of the present invention
herein disclosed should not be limited by the particular disclosed
embodiments described above.